MPM3804

– 0.6A, 5.5V INPUT STEP-DOWN MODULE SYNCHRONOUS

REGULATOR WITH INTEGRATED INDUCTOR IN ULTRA-SMALL 2X2X0.9MM QFN PACKAGE

MPM3804 Rev.1.0

www.MonolithicPower.com

12

5/2/2018

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internally. In light-load condition, the SW on

pulse time is determined by the on-time

generator and AAM comparator.

HS_ driver

VREF

VFB

COT

Generator

EN

IAAM

IL_ sense

R

S

Q

FBCOMP

AAMCOMP

Figure 5: Simplified AAM Control Logic

The MPM3804 uses a ZCD to determine when

the inductor current starts to reverse. When the

inductor current reaches the ZCD threshold, the

low-side switch is turned off.

AAM mode together with the ZCD circuit makes

the MPM3804 work in DCM at light load

Enable (EN)

When the input voltage is greater than the

under-voltage

lockout

(UVLO)

threshold

(typically 2V), the MPM3804 can be enabled by

pulling EN higher than 1.2V. Leave EN floating

or pull EN down to ground to disable the

MPM3804. There is an internal 1M

Ω resistor

from EN to ground.

When the device is disabled, the part goes into

output

discharge

mode

automatically.

The

internal discharge MOSFET provides a resistive

discharge path for the output capacitor.

Soft Start (SS)

The MPM3804 has a built-in soft start (SS) that

ramps up the output voltage at a controlled slew

rate to avoid overshooting at start-up. The soft-

start time is about 0.5ms, typically.

Power

Good

Indicator

(only

for

MPM3804GG-XX)

The MPM3804 has an open drain and requires

an external pull-up resistor (

100kΩ~500kΩ) for

exceeds

the

-10%

window,

the

internal

MOSFET pulls PG to ground. The MOSFET

Current Limit

The MPM3804 has a 1.3A, high-side, switch-

current limit, typically. When the high-side

switch reaches its current limit, the MPM3804

remains in hiccup mode until the current drops.

This

prevents

the

inductor

current

from

continuing to rise and damaging components.

Short Circuit and Recovery

The MPM3804 enters short-circuit protection

(SCP) mode when it reaches the current limit

and attempts to recover with hiccup mode. The

MPM3804 disables the output power stage,

discharges

the

soft-start

capacitor,

and

attempts to soft start automatically. If the short-

circuit condition remains after the soft start

ends, the MPM3804 repeats this cycle until the

short circuit is removed and the output rises

back to regulation levels.